Process for packaging surgical string material



`PROCESS FOR PACKAGING SURGICAL STRING MATERIAL Filed mayl 2, 1941INVENTOR.

Patented Aug. 6, 1946 PROCESS FOR PACKAGING SURGICAL STRING MATERIALGeorge Josh, Crown Point, Ind., assignor to Armour and tion of IllinoisCompany, Chicago, Ill., a corpora- Application May 2, 1941, Serial No.391,618

14 Claims. l

This invention relates to processes of packaging surgical stringmaterial, such as sutures and ligatures, and it is particularlyconcerned with processes in which the string material is dehydrated andsterilized in the presence of a waterimmiscible fluid.

In the packaging of sutures and ligatures it is necessary to dehydratesurgical string material prior to "heat sterilization and it is alsonecessary that the iinished string be sterile and strong. Any traces ofmoisture left in the string interfere with sterilization and, when thestring is held at sterilizing temperatures for a considerable time,weaken the string, or in other Words, cause a decrease in the tensileand knot strength of the string.

It has been the practice in the art to treat the string material withheated air or with dried air to remove moisture, after which the stringis iinmersed in a liquid and heated to eifect sterilization. It is verydiflicult to remove the last traces of moisture in this way and thepresence of such moisture causes weakness in the string uponsterilization, possibly due to hydrolysis of the co1- lagenous matterpresent. Furthermore, the dried string material is quite hygroscopic andthus tends to reabsorb moisture when exposed to moisture-carryingatmosphere after dehydration,

It is an object of my invention to dehydrate the string materialthoroughly and to sterilize the den hydrated string while it is immersedin a waterimmiscible uid. It is a further object of my invention topreserve the tensile and knot strength of the surgical string materialby dehydration and by sterilization while the string is immersed insuitable liquids. -Other objects and advantages of my invention willappear after the detailed description herein give I have found that thedisadvantages of the prior art are overcome and an improved surgicalstring package is produced by heating the surgical string material in anopen container while covered with a water-immiscible fluid containing alower boiling liquid and a higher boiling liquid until at least part ofthe lower boiling liquid has been evaporated 01T and then sterilizingthe string by heating it, immersed in a water-immiscible liquid whichhas a boiling point above the sterilizing temperature. The sterilizedstring material is then stored, suitably in a sealed tube containing anydesired storing or holding fluid.

The iiuid in which the string is immersed during the first heating stepcomprises a low boiling liquid having a boiling point higher than theboiling point of water, for example, a lower boiling (Cl. 12S-335.5)

hydrocarbon such as toluene, a xylene, ethyl benzene and theilike, or awater-insoluble ketone or the like, and a higher boiling liquid having aboiling point higher than the sterilizing temperature, for example, ahigher boiling hydrocarbon such as mesitylene, cymene, decane and thelike, or a water-insoluble ketone or the like. The fluid' mixture ismade up of liquid constituents which are miscible with each other. Amixture readily obtained on the market which contains lower and higherboiling constituents, such as kerosene, may also be used, so long aspart of the mixtureV has a boiling point higher than that of water andis vaporizable below the sterilizing temperature and part of the mixturehas a boiling point higher than the sterilizing temperature.

In the case of non-boilable sutures or ligatures, I have found that animproved surgical string package is produced by immersing the stringmaterial in a container in a water-immiscible fluid mixture as describedabove, heating to Vaporize the lower boiling liquid and tc dehydrate thestring, heating to sterilize while the string is immersed in theremaining higher boiling liquid, cooling, pouring off the sterilizingliquid, adding a suitable tubing or storing fluid and sealing thecontainer. In the case of boilable sutures, the string material isplaced in a container and covered with a watereimmiscible fluidcomprising a low boiling liquid and a higher boiling liquid as describedabove, and heated to vaporize the low boiling liquid and with it themoisture contained in the string material. The higher boiling liquidwhich remains and in which the string is immersed is removed, and tubingor storing fluid, for example, a liquid hydrocarbon, is added, andthereafter the container is sealed off in the customary manner andsterilized.

The attached drawing will helpto illustrate the process of my invention.

Figure 1 is a longitudinal sectional view of onel embodiment of theinvention, showing a glass tube containing a coiled surgical string andthe waterimmiscible fluid prior to the rst heating step; Figure 2 is alongitudinal sectional View of the tube and contents after the Figure 3is a View of a basket having a hinged lid and containing a number oftubes within which are disposed coils of surgical string material:Figure 4 is a sectional view of the basket containing the tubes, thesection being taken on the line A A of Figure 3.

Referring to the drawing in detail, Il? is a glass tube containingsurgical string I2; Il is a waterimmiscible uid comprising a lowerboiling liquid first heating step:

tubing fluid added and a. higher boiling liquid and enough of thsstarting liquid mixture is present so that at the end of the firstheating stage there is suicient liquid Ha, as shown in Figure 2, left tocover the string. The liquid lla comprises predominantly the higherboiling constituent of the starting liquid but smaller amounts of thelow boiling constituent may, of course, still remain.

The tubes are conveniently held in a framen Work or wire basket I3 whichis fitted with a lid 14, such as a Wire mesh lid, fitted by a hinge l5to the top of one wall of the basket and held by a clamp I6 whichsecures it to the top of the opposite wall of the basket. drainage ofliquid from the tubes when the lid is held shut and the basket isinverted. The basket and lid may also be made of perforated sheet metalwhich allows drainage. In the process the tubes containing the coils ofstring are placed in the basket and are iilled with the mixture of lowerand higher boiling liquids. The

basket is then heated as described, thereafter the lid of the basket isclamped in place, the

,basket is inverted until the remaining liquid is drained out of thetubes, the basket is then placed right side up, the lid opened, and thedesired to the tubes.

A t Ezrample As an example of the preparation of my surgical stringpackage, the surgical string material,

suchA as a suture-or ligature, is coiled and inserted into the glasstube l0. A number of these glass tubes 'containing the coiled stringsare placed in a wire basket so that each tube is-maintained in anupright position, the tubes are'lled with a liquid consisting of about25% toluene and about '75% of a commercial cumene fraction having aboilingpoint of about 330 F. and the lid is placed on the basket.Y Thebasket containing the filled tubes is now heated to about 320 F. At theend fof this time substantially all of the toluene will have boiled off,the volume of the liquid being thereby reduced, as shown in Figure 2 andthe string material Will'be dehydrated.

In the case of non-boilable sutures, the tubes containing the remainingcumene liquid and the string material are now sterilized, suitably byheating at about 320 F. for about an hour. The sterilized tubes,disposed within the basket, are nowl cooled as quickly as desired andthe basket is inverted, the lid being held firmly in place, so that thesterilizing fluid is drained from the tubes into any convenientreceptacle, whence it may .later-be recovered. Storing fluid is nowadded,

under aseptic conditions to the sterilized tube Yand the tube is thensealed ofi in the usual manner. Any storing fluid ordinarily used withnonboilable surgical strings may be employed, as, for example, a fluidcomprising about 95% to 98% alcohol and 2% to 5% sterile water with, ifdesired, a small amount of germicide such as potassium mercurio iodide.In the case of boilable surgical strings, the fluid containing dissolvedfat and the like is drained out of the tubes at the end of the iirstheating stage, a storing fluid for boilable strings, such as curnene orxylene, for example, is added and the tubes are sealed off andsterilized, after which the package is ready for storage or marketing.Sterilization of the sutures in sealed tubes may be effected by heatingthe tube and its contents to sterilization temperature ofthe suture inany convenient way.

In the above described process it is advantageous to carry out theheating step while the The mesh lid permits containing the string andVand to prevent building up a concentration of these vapors in the roomwhere the operators work. Under these conditions, heating takes placeunder a slight vacuum. However, I can heat at ordinary pressures orunder any degree of vacuum, which would accelerate the process. Thevapors may be condensed and the solvent vapors recovered for re-use, ifdesired. It is an advantage of my process that cotton plugs are notnecessary in the tubes nor do the tubes have to be sealed ofi from theatmosphere before the sterilizng step. The-string material is coveredwith a water-immiscible liquid or with a layer of water-immiscibleliquid at temperatures below the vaporization point of such liquid,thereby preventing contact of the string with moistureladen air andreabsorption of moisture.

While I have described specific ways of carrying out my process it willbe understood that other specific Ways may be employed, and variouschanges and modifications may be made in the practice of this processwithout departing from the spirit of this invention. The foregoingdetailed description of the process and means for carrying it out hasbeen given for purposes of explanation only and no unnecessarylimitations should be understood therefrom.

Having now described my invention what I wish to claim is:

1. The process of preparing a sterilized surgical string package whichcomprises heating surgical string disposed within an open container,said string being immersed in a water-immiscible uid containing alower-boiling liquid having a boiling point higher than that of waterand being vaporizable below the sterilization temperature and a higherboiling liquid having a boiling point higher than the sterilizingtemperature, until a substantial portion of said lower-boiling liquid isVaporized, thereafter heating to sterilize the said surgical stringimmersed in the remaining liquid, removing the remaining liquid, addinga storing fluid to the container and sealing said container.

2. The process of preparing a sterilized surgical string package whichcomprises heating surgical string disposed within an open container,said string being immersed in a liuid comprising a lower boiling liquidhydrocarbon having a boiling point higher than that of water and beingvaporizable below the sterilization temperature and a higher boilingliquid hydrocarbon having av boiling point higher than the sterilizationtemperature, until a substantial portion of said lowerboilinghydrocarbon is vaporized, thereafter heating to sterilize, removing theremaining fluid, adding a storing iluid to the container and sealingsaid container.

3. The process of preparinga surgical string package which comprisesheating a surgical string disposed within an open tubular container,said string being immersed in a liquid comprising toluene and a cumenefraction having a boiling pint of about 330 F., until the'toluene issubstantially vaporized, and then sterilizing the surgical stringimmersed in the remaining Acumene liquid, removing the cumene liquid,adding a storing fluid to said the container.

4. The process of preparing a sterilized surgical string package whichcomprises heating a surgical string disposed within an open container,said string being immersed in a water-immiscible iluid comprising alower boiling liquid having a boiling point higher than that of waterand being vaporizable at temperatures below the sterilizationtemperature and a higher boiling liquid havcontainer and sealing ing aboiling point higher than the sterilizationl temperature, until asubstantial portion of the said lower boiling liquid is vaporized,removing the remaining liquid, adding a non-aqueous storing fluid tosaid container, sealing said container and sterilizing.

5. 'I'he process of preparing a sterilized surgical string package whichcomprises heating a surgical string disposed within an open container,

said string being immersed in a fluid comprising a lower boiling liquidhydrocarbon having a boiling point higher than that of water and beingvaporizable at a temperature below the sterilization temperature and ahigher boiling liquid hydrocarbon having a boiling point higher than thesterilization temperature, until the lower boiling hydrocarbon issubstantially vaporized, removing the remaining uid, adding anon-aqueous storing iiuid to said container, sealing said container andsterilizing.

6. In a process for preparing a sterilized surgical string package, thesteps which comprise heating surgical string immersed in awaterimmiscible iiuid comprising a lower boiling liquid having a boilingpoint higher than that of water and being vaporizable at a temperaturebelow the sterilization temperature and a higher boiling liquid having aboiling point above the sterilization temperature, until a substantialportion of the said lower boiling liquid is vaporized, while maintainingthe temperature of said fluid below sterilization temperature, andthereafter sterilizing the string immersed in a water-immiscible fluidhaving a boiling point above the sterilization temperature.

7. In a process for preparing a sterilized surgical string package, thesteps which comprise heating a surgical string immersed in a liquidcomprising toluene and a cumene fraction having a boiling point of about330 F., until the toluene is substantially vaporized, while maintainingthe temperature of said liquid below sterilization temperature, andthereafter sterilizing the surgical string immersed in the remainingcumene liquid.

8. In a process for preparing a sterilized surgical string package, thesteps which comprise heating a surgical string immersed in awaterimmiscible fluid comprising a low boiling liquid having a boilingpoint higher Ithan that of water and being vaporizable at a temperaturebelow the sterilizing temperature and a higher boiling liquid having aboiling point above the sterilizing temperature, until a substantialportion of the said lower boiling liquid is vaporized while the stringremains immersed in iiuid and while maintaining the temperature of saidfluid below sterilization temperature, and thereafter heating tosterilize the string immersed in a water-immiscible uid having a boilingpoint higher than the sterilizing temperature.

9. In a process for preparing a sterilized surgical string package, thesteps which comprise heating a surgical string immersed in awaterimmiscible fluid comprising a low boiling liquid having a boilingpoint higher than that of water and being vaporizable at a temperaturebelow the sterilizing temperature, until a substantial portion of thesaid lower boiling liquid is vaporized while the string remains immersedin fluid and while maintaining the temperature of said fluid belowsterilization temperature, and thereafter heating to sterilize thestring immersed in the remaining uid.

10. The process of preparing a surgical string package which comprisesheating surgical string disposed within an open container, said stringbeing immersed in a water-immiscible fluid comprising a lower boilingliquid hydrocarbon solvent having a boiling point higher than that ofwater and being vaporizable at a temperature below the sterilizingtemperature and a higher boiling liquid hydrocarbon solvent, until thesaid lower boiling solvent is substantially vaporized, continuouslywithdrawing the solvent vapors, thereafter heating to sterilize thestring immersed in the remaining liquid, removing the remaining liquid,adding a storing iiuid to said container and sealing said container.

11. In a process for preparing sterilized surgical string the steps ofdehydrating said string while immersed in a water-immiscible uidcomprising a lower boiling liquid having a boiling point higher thanthat of water and vaporizable at a temperature below the sterilizationtemperature and a higher boiling liquid having a boiling point above thesterilization temperature by maintaining said string at a temperature atleast as high as the boiling point of said lower boiling liquid butbelow the sterilization temperature until at least a substantial portionof said lower boiling liquid is vaporized, and sterilizing the thusdehydrated string immersed in a water-immiscible liquid by heating saidstring while so immersed to sterilizing temperature.

12. A process as set forth in claim 11 wherein said dehydrating step isperformed at a pressure at least as low as atmospheric pressure.

13. A method of dehydrating animal material adapted and intended forsurgical purposes which includes heating the same to a water removingtemperature in an organic liquid having a solubility for water nogreater than 5.0% for a sufficient length of time to desirably dehydratesaid material and then cooling, contact between said material and airbeing avoided during both the heating and the cooling steps.

14. A method of treating animal material to dehydrate and sterilize thesame for surgical purposes which includes heating said material to awater-removing temperature which is below the sterilization temperature,in an organic liquid medium which comprises a liquid having a solubilityfor water no greater than 5.0% to desirably dehydrate said material,heating the dehydrated material to sterilization temperature in anorganic liquid medium which comprises a liquid having a boiling pointabove the sterilization temperature and having a solubility for water nogreater than 5.0% to desirably sterilize said material, and then coolingsaid material, contact between said material and air being avoidedduring each of said heating steps.

GEORGE JOSH.

